Total knee arthroplasty method

ABSTRACT

A total knee arthroplasty (TKA) set that includes a universal cutting jig for shaping the distal femur is disclosed, along with corresponding TKA methods. The universal cutting jig may be used to create a shaped femur that can receive multiple and different TKA implant designs. A universal high flexion knee system adapted for left-right use is also disclosed.

This application is a division of U.S. Patent Publication Number US2008/0195108 A1 (U.S. patent application Ser. No. 11/673,991, filed Feb.12, 2007), which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a total knee arthroplasty (TKA) system andmethod, in particular a TKA system and method that include a universalcutting jig for shaping the distal femur and a multitude of TKAprosthesis designs that fit into the same shaped distal femur.

2. Description of Related Art

The TKA systems typically have a distinct profile to the distal femurintegrating a surface specific to the system. This profile can be thesame for the different sizes in a system, but typically is not the samefor different articulating surface designs. Attempts to create cuttingjigs and methods for shaping the distal femur are previously described.Lacey (U.S. Pat. No. 4,502,483) discloses a method for resecting andshaping the distal femur through the use of a cutting jig is a standardpractice for preparing the femur. The method described by Lacey (U.S.Pat. No. 4,502,483) is incorporated by reference in its entirety.Russell et al. (U.S. Pat. No. 4,722,330) and Axelson et al. (U.S. Pat.No. 6,558,391) disclose a similar method for resecting and shaping thedistal femur with various cutting jig designs specifically for receivinga knee prosthesis. Russell et al. (U.S. Pat. No. 4,722,330) and Axelsonet al. (U.S. Pat. No. 6,558,391) are incorporated by reference in theirentirety. The cutting jigs described in the aforementioned prior artaddresses the need to shape the femur and the shaped profile is specificto a single TKA system design. The system specific profile requires thata specific set of instrumentation, including a cutting jig for shapingthe distal femur, be provided. The specificity of the instruments to aTKA system limits the usage of the instrument set solely to one TKAdesign.

The methods and systems described by Lacey, Russel, and Axelson do notaddress the need for multiple TKA femoral component designs for a givenshaped profile. The specificity of the cutting jig to a specific TKAsystem design requires multiple sets of instruments if more than one TKAsystem design is used by a particular surgeon. It is common for asurgeon to use several designs, as patients' anatomies, pathologies, andlifestyles may dictate the need for a wide range of motions that nosingle TKA system design can provide.

Gerbec et al. (U.S. Pat. No. 6,866,683) discloses a modular TKA systemthat offers multiple designs with respect to the portion of the implantthat integrates with the patients' bone. However, the design describesonly one articulating shape profile, and the modular nature of thesystem is to allow for use of this system for primary or revision TKA.This system does not allow for flexibility with articulating surfaceprofile. Furthermore, complex modular systems may be less desirable dueto their inherent complexity and the increased number of regions orcomponents that can each increase the risk for implant failure.

A general overview of the history of TKA systems can be found inRobinson, “The Early Innovators of Today's Resurfacing Condylar Knees,”The Journal of Arthroplasty, Volume 20, Number 1 Supplement 1 2005,pages 2-26.

There is a need in the art for a TKA system that utilizes a universalcutting jig for a variety of TKA articulating profile designs. A systemthat solves this need will reduce the amount of instrumentation requiredfor multiple TKA designs and will provide surgeons with more choices ofTKA profiles for a given surgery.

SUMMARY OF THE INVENTION

A total knee arthroplasty system is disclosed. In one aspect, theinvention provides a system for performing a total knee replacementsurgery comprising: a jig configured to guide a cutting member incutting a distal portion of a femur and resulting in a prepared distalsurface, the prepared distal surface having a prepared shape; a firstfemoral component having a first proximal side; a second femoralcomponent having a second proximal side; the first proximal side and thesecond proximal side being substantially similar and configured toengage the prepared shape; the first femoral component having a firstdistal side; the second femoral component having a second distal side;and wherein the first distal side is shaped differently than the seconddistal side.

In another aspect, the first femoral component includes a correspondingfirst tibial component.

In another aspect, the second femoral component includes a correspondingsecond tibial component.

In another aspect, a third femoral component includes a third proximalside being substantially similar to the first proximal side and whereinthe third femoral component includes a third distal side that is shapeddifferently than either the first distal side or the second distal side.

In another aspect, the jig is smaller than a second jig, the second jigconfigured to guide the cutting member in cutting a second distalportion of a femur and resulting in a second prepared distal surface,the second prepared distal surface having a second prepared shape;wherein the second prepared shape is larger than the prepared shape.

In another aspect, the invention provides a method for performing atotal knee replacement procedure comprising the steps of: preparing adistal femur by cutting the distal femur with a cutting device that isguided by a jig, and eventually forming a prepared distal femur with afirst distal surface; selecting a selected knee prosthesis from a groupof candidate knee prostheses, wherein the group of candidate kneeprostheses includes candidate femoral components having similar proximalsides and having substantially different distal sides; wherein theproximal sides are configured to engage the first distal surface of theprepared distal femur; and associating the selected femoral componentwith the prepared distal femur.

In another aspect, the proximal sides of the candidate knee prosthesisfemoral components include similar proximal surfaces configured toengage the prepared distal surface.

In another aspect, the group of candidate knee prostheses is associatedwith a first size.

In another aspect, the first group of candidate knee prostheses isassociated with a second group of candidate knee prostheses.

In another aspect, the second group of candidate knee prosthesesincludes candidate femoral components having similar proximal sides andhaving substantially different distal sides.

In another aspect, the second group of candidate knee prostheses isassociated with a second size.

In another aspect, the first size is different from the second size.

In another aspect, the invention provides a kit of parts comprising: aset of knee prostheses including a femoral component and a tibialcomponent; each femoral component of the set of knee prosthesesincluding a proximal side and a distal side; wherein the proximal sideof each femoral component is substantially similar in size and shape;wherein the distal side of each femoral component is shaped differently;and wherein each femoral component has a corresponding tibial componentto match the distal side of the femoral component.

In another aspect, the kit of parts further comprises a cutting jig.

In another aspect, the set of knee prostheses are similar in size.

In another aspect, each femoral component is configured to be attachedto a right femur or a left femur.

In another aspect, each knee prosthesis of the set of knee prostheses iscapable of undergoing a high flexion angle.

In another aspect, the high flexion angle is about 150 degrees.

In another aspect, the jig is used to shape the distal end of a femurfor attaching a femoral component.

In another aspect, the invention provides a system for performing atotal knee replacement surgery on a left or right knee comprising: a jigconfigured to guide a cutting member in cutting a distal portion of aleft femur and resulting in a prepared left distal surface, the preparedleft distal surface having a first prepared shape; the jig configured toguide a cutting member in cutting a distal portion of a right femur andresulting in a prepared right distal surface, the prepared right distalsurface having a second prepared shape; and wherein the first preparedshape and the second prepared shape are substantially identical andconfigured to receive a universal femoral component for use in either aright knee or a left knee.

In another aspect, the universal femoral component is an average of aleft femoral component and a right femoral component.

In another aspect, the system includes a set of at least two universalfemoral components.

In another aspect, the proximal sides of each universal femoralcomponent in the set of universal femoral components are similar.

In another aspect, the distal sides of each universal femoral componentin the set of universal femoral components are substantially different.

In another aspect, each universal femoral component of the set ofuniversal femoral components is associated with a distinct tibialcomponent.

In another aspect, the sizes of the universal femoral components aresimilar.

In another aspect, the invention provides a system for performing atotal knee replacement surgery comprising: a jig configured to guide acutting member in cutting a distal portion of a femur and resulting in aprepared distal surface, the prepared distal surface having a preparedshape; a first femoral component having a first proximal side; a secondfemoral component having a second proximal side; the first proximal sideand the second proximal side being substantially similar and configuredto engage the prepared shape; the first femoral component having a firstdistal side that is different from a second distal side of the secondfemoral component; and wherein each femoral component is configured tobe used in a high flexion knee prosthesis. Generally, a high flexionknee is any knee that can bend beyond about 120 degrees.

In another aspect, the high flexion knee prosthesis is able to achieve aflexion angle in the range of 90-150 degrees.

In another aspect, the high flexion knee prosthesis is able to achieve aflexion angle in the range of 109-150 degrees.

In another aspect, the high flexion knee prosthesis is able to achieve aflexion angle in the range of 130-150 degrees.

In another aspect, the first femoral component is a universal femoralcomponent that may be used with either a left femur or a right femur.

In another aspect, the prepared shape is configured to receive theuniversal femoral component.

In another aspect, the first distal end of the first femoral componentis associated with a first tibial component.

In another aspect, the second distal end of the second femoral componentis associated with a second tibial component.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is an isometric view of a preferred embodiment of a universalcutting jig mounted on a distal femur;

FIG. 2 is a schematic cross sectional side view of a preferredembodiment of a universal cutting jig;

FIG. 3 is an isometric view of a preferred embodiment of a distal femurthat has been shaped using the universal cutting jig;

FIG. 4 is a side view of a preferred embodiment of five different TKAsystem designs having the same proximal surface for integrating with theshaped distal femur illustrated in FIG. 3 and different distalarticulating surfaces;

FIG. 5 is a side view of a preferred embodiment of the TKA system thatencompasses six sizes of the 5 different TKA femoral prosthesis designsillustrated in FIG. 4;

FIG. 6 is a top down view of a preferred embodiment of a left and rightfemoral prosthesis;

FIG. 7 is a top down view of a preferred embodiment of a left and rightfemoral prosthesis averaged together;

FIG. 8 is a top down view of a preferred embodiment of a universalfemoral prosthesis;

FIG. 9 is a side view of a preferred embodiment of a universalreplacement knee undergoing bending; and

FIG. 10 is a side view of a preferred embodiment of a universalreplacement knee achieving a high flexion angle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a preferred embodiment of a universal cutting jig 100for shaping distal femur 101. Universal cutting jig 100 may be anydevice configured to shape the distal end of a femur. In someembodiments, universal cutting jig 100 may be rectangular, as seen inthe current embodiment, however in other embodiments; universal cuttingjig 100 may be configured to have any shape.

Generally, universal cutting jig 100 may be made of any material that iscommonly used for making jigs. In some embodiments, universal cuttingjig 100 may be made of metal or similar materials. In a preferredembodiment, universal cutting jig 100 may be made of a materialincluding stainless steel. In some embodiments, stainless steel is used;however, titanium or any other suitable material may also be used.

Preferably, universal cutting jig 100 includes provisions for beingtemporarily fixed to distal femur 101. In some embodiments, universalcutting jig 100 may be attached to distal femur 101 using handle 189 ora similar device. In other embodiments, any type of clamp or otherdevice may be used that are well known in the art for securing cuttingjigs to femurs.

Universal cutting jig 100 may include provisions for shaping distalfemur 101. In a preferred embodiment, the shaping of distal femur 101 isperformed with the use of an oscillating surgical saw having a blade forcutting bone. The blade may be guided along defined cutting planesthrough distal femur 101 that are established with the use of theuniversal cutting jig 100.

In this preferred embodiment, universal cutting jig 100 may includefirst horizontal slot 105 and second horizontal slot 106. Preferably,universal cutting jig 100 may also include horizontal recess 107 thatmay be generally wider than horizontal slots 105 and 106. Additionally,universal cutting jig 100 may include first diagonal slot 108 and seconddiagonal slot 119. Diagonal slots 108 and 119 preferably extend throughuniversal cutting jig 100. Each of these slots 105, 106, 108 and 119, aswell as horizontal recess 107, are preferably configured to accept thecutting blade along predetermined cutting planes defined by slots 105,106, 108 and 119. Thus, a surgeon may shape distal femur 101 in aprecise manner, reducing the chances for unwanted deviations from thepreferred shape for distal femur 101.

FIG. 3 shows a preferred embodiment of the distal femur 101 afterprepared distal surface 200 has been shaped with universal cutting jig100. Generally, prepared distal surface 200 comprises individual planesthat are formed using a cutting device in conjunction with universalcutting jig 100. First upper plane 251 is preferably associated withfirst horizontal slot 105. Likewise, first lower plane (not shown inFIG. 3) may be associated with second horizontal slot 106. Additionally,diagonal slots 108 and 119, as well as the associated diagonal slots onthe second side of universal cutting jig 100, are preferably associatedwith first sloped surface 252 and second sloped surface 253. Holes 255may have been formed to assist in attaching universal cutting jig 100 todistal femur 101. Finally, inner surfaces 254 and vertical surfaces 256are generally prepared with a different type of tool or jig.

Preferably, multiple knee prostheses may be associated with distal femur101 as it has been shaped using universal cutting jig 100. FIG. 4 is apreferred embodiment of a set of candidate femoral and tibial componentsthat may be associated with distal femur 101. Femoral and tibialcomponents are pieces of a knee prosthesis configured to attach to thefemur and tibia, respectively. Generally, a femoral component and atibial component together make up a total knee arthroplasty (TKA)system.

In the current embodiment, distal femur 101 may be associated withdistinct femoral components from five different TKA systems. In thisembodiment, distal femur 101 may be associated with first femoralcomponent 210, second femoral component 211, third femoral component212, fourth femoral component 213 and fifth femoral component 214. Inthis embodiment, first femoral component 210 is preferably configuredwith proximal side 110 that is shaped to fit together with distalsurface 200 of distal femur 101. Likewise, each of the remaining femoralcomponents 211-214 are preferably configured with a similar proximalside 110 that is shaped to fit together with distal surface 200 ofdistal femur 101. Proximal side 110 may include an optional projectionor pin that mates with residual holes 255 (see FIG. 3) in distal femur101. In other words, the preferred shape of prepared distal surface 200is a specific geometry that, for a given size of implant, will mate withall five distinct femoral components.

Since each of the femoral components 210-214 have substantially similarproximal sides 110 for integrating with the shaped distal femur 101,this means a single universal cutting jig 100 may be used to preparedistal femur 101 for any number of compatible femoral components. Aslong as the femoral component includes a compatible proximal side 110,that femoral component may be used with the distal surface 200 that hasbeen shaped using universal cutting jig 100. Although five distinctfemoral components 210-214 are shown in this embodiment, otherembodiments may include more or less than five distinct femoralcomponents. Preferably, any additional femoral component that may beassociated with distal femur 101 includes a proximal side substantiallysimilar in shape to proximal side 110, in order to fit properly withdistal surface 200.

In some embodiments, other facets may be included as part of theproximal side of a femoral component. For example, fourth femoralcomponent 213, in the preferred embodiment, includes first side wall260. Likewise, fifth femoral component 214 preferably includes secondside wall 262 and protruding portion 264. These additional facets ofproximal sides 110 of femoral components 213 and 214 may correspond tovarious additional surfaces of prepared distal surface 200 of distalfemur 101 that may be configured using additional tools.

Each femoral component 210-214 also includes a distal side, configuredto attach to various tibial components. As shown in FIG. 4, firstfemoral component 210 includes first distal side 220, second femoralcomponent 211 includes second distal side 221, third femoral component212 includes third distal side 222, fourth femoral component 213includes fourth distal side 223, and fifth femoral component 214includes fifth distal side 224.

Preferably, distal sides 220-224 may be different from one another inshape and design. As seen in FIG. 4, each distal surface 220-224 has aslightly different curvature. Distal sides 220-224 may have similarprofiles to the distal sides of femoral components already offered bymanufacturers of TKA systems. For example, first distal side 220 may bethe profile of a TKA femoral component offered by Stryker Orthopedicswhile second distal side 221 may be similar to a profile offered byZimmer Orthopedics. The remaining distal surfaces may be similar toother commercially available TKA systems or be unique or proprietarydesigns.

Each distal side 220-224 is preferably configured to mate with adistinct tibial component. A tibial component may be configured toattach to the tibia bone at one end, and to attach to or be associatedwith femoral component at another end. The connection between a femoralcomponent and a tibial component then functions as the knee joint. Inthe example shown in FIG. 4, first femoral component 210 includes acorresponding first tibial component 215, second femoral component 211includes a corresponding second tibial component 216, third femoralcomponent 212 includes a corresponding third tibial component 217,fourth femoral component 213 includes a corresponding fourth tibialcomponent 218, and fifth femoral component 214 includes a correspondingfifth tibial component 219.

Tibial components 215-219 preferably have inner surfaces to match withthe femoral component designs. For example, first distal side 220 offirst femoral component 210 is preferably shaped to fit within firstinner surface 270 of first tibial component 215. The curved nature offirst distal side 220 and first inner surface 270 preferably allowsfirst femoral component 210 to slide against first tibial component 215.This configuration allows the TKA system to simulate the bending of aknee, as will be discussed in further detail below.

In a manner similar to first distal side 220 and first inner surface270, second distal side 221 preferably fits within second inner surface271 of second tibial component 216; third distal side 222 preferablyfits within third inner surface 272 of third tibial component 217;fourth distal side 223 preferably fits within fourth inner surface 273of fourth tibial component 218; and fifth distal side 224 preferablyfits within fifth inner surface 274 of fifth tibial component 219. Eachof these femoral components is preferably configured to slide within orwith respect to the corresponding tibial components, in a manner similarto the movement described for first femoral component 210 and firsttibial component 215.

Although FIG. 4 shows an embodiment with five possible femoral andtibial components, some embodiments may provide more or less than fivepossible femoral and tibial components. Any desired number of femoraland tibial components may be provided and it should be kept in mind thatthe embodiment shown in FIG. 4 is merely an example.

Providing similar proximal surfaces 110 to each femoral component210-214 provides the surgeon with some flexibility in making decisions.In one example, a surgeon may decide which femoral component or TKAsystem to attach to distal femur 101 during a surgical procedure, evenafter distal femur 101 has been shaped, since each femoral component isconfigured to fit with a single preconfigured distal surface of distalfemur 101. This decision making flexibility would not be possible withother TKA systems where a particular cutting jig is needed for eachdifferent TKA system. With these other TKA systems, once the distalfemur has been shaped, only the corresponding femoral component may beimplanted. For example, if the system offered by Stryker was used toshape the distal femur and it was later discovered during the surgery,and after the distal femur was shaped, that the system offered by Zimmerwould be a more suitable design, the surgeon could not implant theZimmer femoral component onto a distal femur shaped by the Strykersystem.

Throughout the remainder of this detailed specification, any set of kneeprostheses configured to attach to the same distal surface shape will bereferred to as a universal TKA system.

In some embodiments, universal TKA systems may be provided in differentsizes. Any desired number of sizes of universal TKA systems may beprovided. One example of a series of universal TKA systems in differentsizes is illustrated in FIG. 5, where six sizes of universal TKA systemsare shown. Of course it is possible to provide more or less than sixsizes of universal TKA systems. The embodiment shown in FIG. 5 is merelyan example.

Referring to FIG. 5, first distal femur surface 199 corresponds to afirst set of femoral components 109. Each of the femoral components ofthe first set of femoral components 109 preferably includes asubstantially similar proximal surface that is configured to mate withfirst distal femur surface 199. First distal femur surface 199 may beprepared with a first universal cutting jig (not shown). For clarity,tibial components that correspond to each of the femoral components ofthe first set of femoral components 109 are not shown in FIG. 5, but maybe provided with each of the femoral components. The first universalcutting jig along with the first set of femoral components 109 and theircorresponding tibial components may be referred to as the firstuniversal TKA system. As shown schematically in FIG. 5, the firstuniversal TKA system can be provided in a first relatively small size.

Second distal femur surface 201 corresponds with a second set of femoralcomponents 111. Each of the femoral components of the second set offemoral components 111 preferably includes a substantially similarproximal surface that is configured to mate with second distal femursurface 201. Second distal femur surface 201 may be prepared with asecond universal cutting jig (not shown). For clarity, tibial componentsthat correspond to each of the femoral components of the second set offemoral components 111 are not shown in FIG. 5, but may be provided witheach of the femoral components. The second universal cutting jig alongwith the second set of femoral components 111 and their correspondingtibial components may be referred to as the second universal TKA system.As shown schematically in FIG. 5, the second universal TKA system may belarger than the first universal TKA system.

Third distal femur surface 202 corresponds with a third set of femoralcomponents 112. Each of the femoral components of the third set offemoral components 112 preferably includes a substantially similarproximal surface that is configured to mate with third distal femursurface 202. Third distal femur surface 202 may be prepared with a thirduniversal cutting jig (not shown). For clarity, tibial components thatcorrespond to each of the femoral components of the third set of femoralcomponents 112 are not shown in FIG. 5, but may be provided with each ofthe femoral components. The third universal cutting jig along with thethird set of femoral components 112 and their corresponding tibialcomponents may be referred to as the third universal TKA system. Asshown schematically in FIG. 5, the third universal TKA system may belarger than the second universal TKA system.

Fourth distal femur surface 203 corresponds with a fourth set of femoralcomponents 113. Each of the femoral components of the fourth set offemoral components 113 preferably includes a substantially similarproximal surface that is configured to mate with first distal femursurface 203. Fourth distal femur surface 203 may be prepared with afourth universal cutting jig (not shown). For clarity, tibial componentsthat correspond to each of the femoral components of the fourth set offemoral components 113 are not shown in FIG. 5, but may be provided witheach of the femoral components. The fourth universal cutting jig alongwith the fourth set of femoral components 113 and their correspondingtibial components may be referred to as the fourth universal TKA system.As shown schematically in FIG. 5, the fourth universal TKA system may belarger than the third universal TKA system.

Fifth distal femur surface 204 corresponds with a fifth set of femoralcomponents 114. Each of the femoral components of the fifth set offemoral components 114 preferably includes a substantially similarproximal surface that is configured to mate with fifth distal femursurface 204. Fifth distal femur surface 204 may be prepared with a fifthuniversal cutting jig (not shown). For clarity, tibial components thatcorrespond to each of the femoral components of the fifth set of femoralcomponents 114 are not shown in FIG. 5, but may be provided with each ofthe femoral components. The fifth universal cutting jig along with thefifth set of femoral components 114 and their corresponding tibialcomponents may be referred to as the fifth universal TKA system. Asshown schematically in FIG. 5, the fifth universal TKA system may belarger than the fourth universal TKA system.

Sixth distal femur surface 205 corresponds with a sixth set of femoralcomponents 115. Each of the femoral components of the sixth set offemoral components 115 preferably includes a substantially similarproximal surface that is configured to mate with sixth distal femursurface 205. Sixth distal femur surface 205 may be prepared with a sixthuniversal cutting jig (not shown). For clarity, tibial components thatcorrespond to each of the femoral components of the sixth set of femoralcomponents 115 are not shown in FIG. 5, but may be provided with each ofthe femoral components. The sixth universal cutting jig along with thesixth set of femoral components 115 and their corresponding tibialcomponents may be referred to as the sixth universal TKA system. Asshown schematically in FIG. 5, the sixth universal TKA system may belarger than the firth universal TKA system.

Additional universal TKA systems of different sizes may also beprovided. For example, embodiments may include seventh, eighth and ninthuniversal TKA systems that are larger than the sixth universal TKAsystem. Any desired number of universal TKA systems in any number ofsizes may be provided.

Because the proximal surfaces of each set of femoral components aresubstantially similar for a given size, the universal TKA systemprovides multitude TKA femoral prosthesis designs for a given size femuralong with a multitude of sizes to accommodate the variation in anatomypatient to patient. This universal TKA system can provide significantlogistical benefits to hospitals and surgical centers because only asingle universal cutting jig needs to be stocked for each size. Theuniversal cutting jig for a particular size can be used to prepare thedistal femur, and any desired compatible TKA system can then beimplanted. Without this universal TKA system, hospitals and surgicalcenters need to stock a particular cutting jig with each different TKAsystem. This can add significant complexity and cost to the storage andmanagement of TKA systems.

Typically, femoral prosthesis designs are configured for either a leftor right femur and tibia. FIG. 6 illustrates an embodiment of a femoralprosthesis design where left femoral component 300 is attached to leftfemur 350 and associated with left tibia 305. In particular, femoralcomponent 300 is larger along first medial side 302, to accommodate thegeneral shape of left femur 350. Likewise, right femoral component 301is attached to right femur 351 and associated with right tibia 306. Inthis case, right femoral component 301 is larger along second medialside 303, to accommodate the general shape of right femur 351.

Preferably, a universal TKA system includes provisions for associating afemoral component with either a left or right femur and the associatedleft and right tibia. To achieve this, universal femoral component 310,seen in FIGS. 7 and 8, may be configured to be the average of rightfemoral component 301 and left femoral component 300. In other words,universal femoral component 310 is not configured to fit either a leftfemur or a right femur exactly, but universal femoral component 310 mayinstead be configured to approximately fit both a left femur and a rightfemur. In a preferred embodiment, an average shape is used; however, inother embodiments, any desired shape that can be used for both left andright configurations may be used.

Additionally, universal femoral component 310 may be configured to matewith tibia 311, which is seen from FIGS. 7 and 8 to be an average ofright tibia 306 and left tibia 305. In other words, universal femoralcomponent 310 may not be configured to fit left tibia 305 or right tibia306 exactly, but universal femoral component may instead be configuredto fit universal tibial component 311.

Universal patella component 360 can be symmetric or asymmetric in shapeand be configured to mate with the femoral patella groove 361. As isknown in the art, patella component 360 is preferably mounted to theprepared under surface of patella 902 (see FIG. 9). Possible patellacomponents that may be used are disclosed in Scott et al. (U.S. Pat. No.5,593,450) and Imbert (U.S. Pat. No. 4,344,192), the entirety of bothpatents are hereby incorporated by reference.

Using this preferred configuration, the femoral prosthesis designdiscussed throughout this detailed description may be used universallywith either a left or right knee. This universal left/rightconfiguration may further reduce the number of components that must bestored in a hospital, for various TKA systems. Instead of having tostore a set of left femoral components and right femoral components, thehospital or surgical center may only need to store a single set ofuniversal femoral components, effectively reducing the number of storedcomponents in half.

It should be understood that the current femoral prosthesis design mayalso be used universally with either a left or right high flexion kneeprosthesis. The term, “high flexion knee,” as used throughout thisspecification and claims means a knee that can bend 120 degrees or more.Generally, a high flexion knee prosthesis is able to undergo about a 150degree flexion angle, similar to the high flexion angle achieved by ahuman knee. This is in contrast to previous prostheses where the maximumflexion angle has been restricted to smaller angles, such as 109degrees. A high flexion knee system may be especially important in Asianand African countries, where squatting and kneeling may be an integralpart of daily life.

FIGS. 9 and 10 are schematic side cross sectional views of universalreplacement knee 802 that has been attached using a universal TKAsystem, undergoing bending. In this preferred embodiment, universalreplacement knee 802 comprises femoral component 804 and tibialcomponent 806, attached to femur 808 and tibia 810, respectively, andpatella component 360 attached to patella 902.

In this embodiment, femoral component 804 includes proximal side 820configured to fit with prepared distal surface 822 of femur 808.Preferably, prepared distal surface 822 has been formed using auniversal cutting jig, as discussed previously. Femoral component 804further includes distal side 826, configured to contact inner surface828 of tibial component 806. As seen in the figures, tibial component806 has been implanted into tibia 810, and in particular, protrusion 830has penetrated into tibia 810.

Preferably, femoral component 804 and tibial component 806 may move in away that allows femur 808 and tibia 810 to bend. As previouslydiscussed, distal side 826 may slide within inner surface 828, allowingfor this movement. In FIG. 9, replacement knee 802 has a flexion angleof 45 degrees. In other words, first central axis 814, associated withtibia 810, is disposed at an angle of 45 degrees from second centralaxis 812 that is associated with femur 808. This amount of bendingrepresents a light degree of bending that may occur during walking orsimilar activities.

In FIG. 10, replacement knee 802 has a flexion angle of about 150degrees, similar to the maximum flexion angle achieved with the humanknee. This high flexion angle may be associated with activities such assquatting or kneeling. Thus, using the universal TKA system discussedthroughout this detailed description, a user may experience the fullrange of motion in the knee. This is in contrast to previous TKAsystems, where a prosthesis may achieve a high flexion angle but may notbe used with both the left and right sides.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A method for performing a total knee replacementprocedure comprising: preparing a distal femur by cutting the distalfemur with a cutting device that is guided by a jig, and eventuallyforming a prepared distal femur with a first distal surface; selecting aselected knee prosthesis from a group of candidate knee prostheses,wherein the group of candidate knee prostheses includes candidatefemoral components having similar proximal sides and havingsubstantially different distal sides, and wherein the proximal sides areconfigured to engage the first distal surface of the prepared distalfemur; and associating the femoral component of the selected kneeprosthesis with the prepared distal femur, wherein the group ofcandidate knee prostheses includes candidate tibial components, whereineach candidate tibial component has an inner surface shaped to receive adistal surface of one of the candidate femoral components, but notdistal surfaces of the remaining candidate femoral components, whereinthe candidate femoral components are configured to be used with either aleft femur or a right femur, wherein the candidate tibial components areconfigured to be used with either a left tibia or a right tibia, andwherein the candidate femoral components are configured to engage theirrespective candidate tibial components with a flexion angle of greaterthan 120 degrees.
 2. The method according to claim 1, wherein theproximal sides of the candidate knee prosthesis femoral componentsinclude similar proximal surfaces configured to engage the prepareddistal surface.
 3. The method according to claim 1, wherein the group ofcandidate knee prostheses is associated with a first size.
 4. The methodaccording to claim 3, wherein the group of candidate knee prosthesescomprises a first group of candidate knee prostheses that is associatedwith a second group of candidate knee prostheses.
 5. The methodaccording to claim 4, wherein the second group of candidate kneeprostheses includes candidate femoral components having similar proximalsides and having substantially different distal sides.
 6. The methodaccording to claim 5, wherein the second group of candidate kneeprostheses is associated with a second size.
 7. The method according toclaim 6, wherein the first size is different from the second size. 8.The method according to claim 1, wherein selecting the selected kneeprosthesis occurs during surgery and after the distal femur is prepared.9. The method according to claim 1, wherein each of the candidatefemoral components comprises approximately an average of a left femoralcomponent and right femoral component, and wherein each of the candidatetibial components comprises approximately an average of a left tibialcomponent and a right tibial component.
 10. The method according toclaim 1, further comprising: selecting the selected knee prosthesisduring a surgical procedure after forming the prepared distal femur;attaching the femoral component of the selected knee prosthesis to theprepared distal femur after selecting the selected knee prosthesis; andimplanting the tibial component corresponding to the attached femoralcomponent such that the attached femoral component and the implantedtibial component are engaged.
 11. The method according to claim 10,further comprising implanting a symmetric universal patella componentthat mates with the attached femoral component.
 12. A method forperforming a total knee replacement procedure comprising: selecting auniversal cutting jig from a plurality of universal cutting jigs,wherein the plurality of universal cutting jigs includes a single typeof universal cutting jig for each femur size, wherein each of theplurality of universal cutting jigs is configured to guide a cuttingdevice to prepare a distal femur, and wherein the selected universalcutting jig corresponds to a particular femur size of a patient; usingthe selected universal cutting jig to prepare a distal femur of thepatient; selecting, from among a plurality of femoral components, afemoral component suitable for the patient, wherein the plurality offemoral components includes a plurality of femoral components for eachfemur size, wherein each of the plurality of femoral components has adistinct distal side and a uniform proximal side configured to engage adistal femur prepared by a corresponding universal cutting jig, whereineach of the plurality of femoral components is configured to be usedwith either a left femur or a right femur, and wherein the selectedfemoral component has a uniform proximal side configured to engage thepatient's distal femur prepared by the selected universal cutting jigcorresponding to the particular femur size of the patient; attaching theselected femoral component to the prepared distal femur of the patient;selecting, from among a plurality of tibial components, a tibialcomponent having a distinct inner surface configured to engage thedistinct distal side of the selected femoral component, wherein theplurality of tibial components includes a plurality of tibial componentsfor each femur size, wherein each of the plurality of tibial componentshas a distinct inner surface shaped to engage a distinct distal side ofa corresponding femoral component at a flexion angle of greater than 120degrees, and wherein each of the plurality of tibial components isconfigured to be used with either a left tibia or a right tibia; andimplanting the selected tibial component in the patient such that thedistinct inner surface of the selected tibial component engages thedistinct distal side of the selected femoral component.
 13. The methodaccording to claim 12, wherein selecting the femoral component suitablefor the patient occurs during surgery and after the distal femur of thepatient is prepared.
 14. The method according to claim 12, wherein eachof the plurality of femoral components comprises approximately anaverage of a left femoral component and right femoral component, andwherein each of the plurality of tibial components comprisesapproximately an average of a left tibial component and a right tibialcomponent.
 15. The method according to claim 12, further comprising:selecting, from among a plurality of symmetric universal patellacomponents, a symmetric universal patella component suitable for theselected femoral component; and implanting the selected symmetricuniversal patella component in the patient mated with the selectedfemoral component.
 16. The method according to claim 12, wherein each ofthe plurality of femoral components is symmetric, and wherein each ofthe plurality of tibial components is symmetric.
 17. The methodaccording to claim 12, further comprising stocking in a surgicalfacility the plurality of universal cutting jigs, the plurality offemoral components, and the plurality of tibial components.
 18. A methodfor storing, managing, and implanting total knee replacement systemscomprising: using a universal cutting jig to prepare a distal femursurface on a patient, wherein the universal cutting jig is configured toguide a cutting device to cut a distal femur surface of a femur of agiven femur size, and wherein the universal cutting jig is configured tobe used on either a left femur or a right femur; selecting, from among astock of a plurality of types of femoral components, a femoral componentof a type suitable for the patient, wherein each of the femoralcomponents of the stock of the plurality of types of femoral componentsis configured for the given femur size, and wherein each femoralcomponent type has a uniform proximal side configured to engage theprepared distal femur surface, has a distinct distal side, and isconfigured to be used on either a left femur or a right femur; attachingthe selected femoral component to the prepared distal femur surface ofthe patient; selecting, from among a stock of a plurality of types oftibial components, a tibial component of a type having a distinct innersurface matching the distinct distal side of the selected femoralcomponent, wherein each of the tibial components of the stock of theplurality of types of tibial components is configured for the givenfemur size, and wherein each tibial component type has a distinct innersurface shaped to engage the distinct distal side of a correspondingfemoral component type at a flexion angle of greater than 120 degreesand is configured to be used with either a left tibia or a right tibia;and implanting the selected tibial component in the patient such thatthe distinct inner surface of the selected tibial component engages thedistinct distal side of the selected femoral component.
 19. The methodaccording to claim 18, further comprising selecting the femoralcomponent of the type suitable for the patient during surgery and afterthe prepared distal femur surface is prepared.
 20. The method accordingto claim 18, further comprising: selecting, from among a plurality ofsymmetric universal patella components for the given femur size, asymmetric universal patella component suitable for the selected femoralcomponent; and implanting the selected symmetric universal patellacomponent in the patient mated with the selected femoral component. 21.The method according claim 18, further comprising stocking in a surgicalfacility the universal cutting jig, the plurality of types of femoralcomponents, and the plurality of types of tibial components.